Unbonded prestress and steel-concrete composite reinforcement design method for concrete T-shaped beams

Abstract

The invention discloses an unbonded prestress and steel-concrete composite reinforcement design method for concrete T-shaped beams. The unbonded prestress and steel-concrete composite reinforcement design method includes steps of firstly, determining unbonded prestress and steel plate-concrete composite reinforcement structures for the reinforcement T-shaped beams; secondly, determining structural parameters of the T-shaped beams prior to reinforcement; thirdly, determining structural parameters of the composite reinforcement structures, to be more specific, initializing the parameters, computing the maximum theoretical thicknesses of reinforcement steel plates, determining the thicknesses of the reinforcement steel plates and the thickness of concrete and determining the heights of longitudinal side steel plates and the widths of bottom steel plates. Each composite reinforcement structure comprises the corresponding bottom steel plate, the two longitudinal side steel plates and a steel bushing case, each steel bushing case comprises two end blocking steel plates, and a plurality of unbonded prestress reinforcing steel bars are arranged in each steel bushing case. The unbonded prestress and steel-concrete composite reinforcement design method has the advantages that the steps are simple, the unbonded prestress and steel-concrete composite reinforcement design method is reasonable in design and convenient to implement, good service effects can be realized, the structural parameters of the bridge composite reinforcement structures can be easily, conveniently and quickly determined, the bridge composite reinforcement structures designed by the aid of the unbonded prestress and steel-concrete composite reinforcement design method are economical and practical, and good reinforcement effects can be realized by the bridge composite reinforcement structures.

Description

technical field [0001] The invention belongs to the technical field of bridge reinforcement, and in particular relates to a design method for the unbonded prestressed and steel-concrete combined reinforcement of a concrete T-shaped beam. Background technique [0002] According to the survey in 2007, there are more than 570,000 bridges in my country, of which there are more than 98,600 dangerous bridges, accounting for about 17%. Affected by various diseases and disaster damage, resulting in a decline in carrying capacity, unable to meet the needs of transportation. It is imminent to repair and strengthen these bridge structures. Therefore, the research on bridge repair, reinforcement and transformation technology has become an important direction of bridge science and technology development. At present, the reinforcement of the upper structure of the bridge mainly adopts the methods of pasting steel plates and pasting carbon fiber cloth. During the reinforcement application ...

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Problems solved by technology

Although the above-mentioned external prestressed concrete reinforcement method can play the role of prestressed reinforcement to a certain extent, it has the following disadvantages: First, it is necessary to add a layer of concrete with a thickness of about 20cm to 50cm on the side or bottom of the beam. , the self-weight of the bridge increases greatly, and the appearance is irregular, which affects the appearance; second, the prestressed tendons are exposed in the air, and measures need to be taken regularly to prevent the prestressed tendons from rusting, maintenance is difficult, and the maintenance cost is high; third, the newly added The dynamic performance of prestressed tendons is poor, and shock absorbers need to be installed to reduce the resonance effect of prestressed tendons and structures; The steering block is used to realize the stress concentration at the steering block and the anchor block; once the steering block is loosened or slipped, it will cause a huge loss of prestress or even failure of the prestress; fifth, the contribution to the stiffness of the original structure is very limited

However, when using prestressed reinforcement and steel plate-concrete composite reinforcement methods to strengthen bridges, the structural design of the composite reinforcement structure is very important. Whether the reinforcement structure design is reasonable or not directly affects the reinforcement cost and reinforcement effect of the bridge. Not only the input cost is high, but the economy is poor. And it leads to unreasonable stress and poor mechanical properties of the reinforced bridge

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